Hydraulic hoisting



30, 196 J. A. M LELLAN HYDRAULIC HOISTING INVENTOR. JAMES A. Mac LELLAN 5 Sheets-Sheet 1 Filed May 17, 1965 Q WQ S Agent Aug. 30, 1966 J. A. M LELLAN HYDRAULIC HOISTING 5 Sheets-Sheet 2 Filed May 17, 1965 FIG. 3

INVENTOR. JAMES A. Mac LELLAN Agent Aug. 30, 1965 .J. A. M LELLAN HYDRAULIC HOISTING 5 Sheets-Sheet 3 Filed May 17, 1965 I N VENTOR JAMES A. Mac LELLAN Agent 0, 1966 J. A. M LELLAN 3,269,777

HYDRAULIC HOI STING Filed May 17, 1965 5 Sheets-Sheet 4 ROCK r0 DEWATER/NG MAKEUP M/ LL 234 B/N 224 WATER SURFACE MEASURING POCKET INVENTOR. JAMES A. Mac LELLAN BY Agent Aug. 30, 1966 J. A. M LELLAN HYDRAULIC HOISTING Filed May 17, 1965 5 Sheets-Sheet 5 HYDRAULIC W H \Jfl H HO/ST PIPE 230 DEWA TER/NG 1 \i BIN Agent United States Patent 3,269,777 HYDRAULIC HOISTING James A. MacLellan, Lynn Lake, Manitoba, Canada, assignor to Sherritt Gordon Mines Limited, Toronto, Ontario, Canada, a company of Canada Filed May 17, 1965, Ser. No. 456,430 20 Claims. (Cl. 302-14) This invention relates to an improved system for hydraulic hoisting and is particularly directed to the hydraulic hoisting of particulated ores and the like discrete solids.

Systems are known for the vertical hoisting of crushed ores utilizing a continuously rising column of water medium flowing at a rate faster than the settling velocity of the ore elevated. Such a system is disclosed in United States Patent No. 2,793,082 wherein two columns of liquid are confined in two upright pipes connected at the bottom to provide a static balance of liquid in both columns. A source of pressure head is provided at the top of one column and an upward velocity in the hoisting column. A system of locked chambers, in series, is provided near the lower end of the columns for introducing particles of ore into the column of upwardly flowing liquid against the static pressure without opening said column of upwardly flowing liquid to the atmosphere.

The present invention constitutes an improvement on this prior hoisting system in that it provides a simplified system of concentric columns in static balance for the introduction of particles of ore to the upwardly flowing :liquid in the central column, the velocity of the downwardly flowing liquid in the annular column being utilized, in part, to facilitate entry of ore particles into the system by way of a single chamber at a level below the bottom of the columns.

It is, therefore, an important object of the present invention to provide a positive-acting system for the hydraulic hoisting of discrete solids such as particles of ore which can be readily adapted for installation in mine openings.

It is another important object of the present invention to provide a hydraulic hoisting system which will receive ore particles from a source at atmospheric pressure and elevate said we particles, of varying sizes and specific gravities, to a delivery level in a single stage lift.

Another object of the present invention is the provision of a hydraulic hoisting system which is simple and economic in operation and which requires a minimum of maintenance and supervision.

These and other objects of the present invention, and the manner in which they can be attained, will become apparent from the following detailed description of the drawings in which:

FIGURE 1 is a perspective view of a hydraulic hoist system of the present invention illustrating the general relationship of the component parts;

FIGURES 2, 3 and 4 are sectional views, partly in elevation, of embodiments of valve mechanisms of the type used in the hoist system of FIGURE 1;

FIGURE 5 is a sectional view, partly in elevation, of an embodiment of hoist chamber of the present invention;

FIGURES 6 and 7 are sectional views, partly in elevation, of embodiments of valve mechanisms of the type used in the hoist chamber of FIGURE 5;

FIGURE 8 is a schematic view of an embodiment of a hydraulic hoist system of the present invention adapted for use in a mine opening;

FIGURE 9 is a side elevation, in more detail, of the dewatering and conveying apparatus illustrated generally in FIGURE 8; and

FIGURE 10 is a vertical transverse section taken along line 1010 of FIGURE 9.

Like reference characters refer to like parts throughout the description of the drawings.

Referring now with particular reference to FIGURE 1 of the drawings, the hoisting system of the present invention comprises central ore hoisting column designated by numeral 10 having a liquid medium such as water flowing upwardly in central pipe 12 and annular liquid supply column designated by numeral 14 having a liquid flowing downwardly in the annulus defined between central pipe 12 and outer pipe 16. A pressure head is imparted to the annular column of liquid 14 by pump 18 in communication therewith by flow line 20. Pump 1-8, together with ancillary equipment for receiving and de-watering the orebea-ring slurry from ore hoisting column 10 and preparing the recovered water for re-cycle such as settling tank 22, transfer pump 24, hydroclone 26 and surge tank 28, is stationed at the level of the upper delivery point. If it is desired to separate fine solids from the system, transfer pump 24 feeds hydroclone 26 through lines 23 and and the vortex overflow from the hydroclone is conducted by line 27 to surge tank 28 with concentrated solids from the apex underflow conducted to the mill for beneficiation. If it is preferred to maintain fine solids in the liquid medium to increase the effective medium specific gravity and thus enhance the lifting effect of medium in hoisting column 10, pump 24 by-passes hydroclone 26 and conducts the medium directly to surge tank 28 through line 29 for re-cycle to the system. The operation of control valves 3031 normally is regulated automatically by a density controller 33 to maintain the desired amount of fines in the liquid medium. Make-up water can be added to the system by line 35 as required.

Annular column 14 extends from the delivery level down to the proximity of apex 32 of loading chamber 34 where, in the embodiment of FIGURE 1, as illustrated more fully in FIGURES 2-4, outer pipe 16 is open-ended and is in continuous communication with the open end of central pipe 12 to maintain columns 10 and 14 in static balance. Apex valve 36, preferably a hydraulic valve comprising a cylindrical ram 38, as will be described in detail hereinbelow, seals and isolates columns 10 and 14 from chamber 34 during the loading step of the operating cycle to permit entry of solids from feed hopper 42 into chamber 34 at atmospheric pressure. Valve 44 in conduit 46, preferably a quick-acting hydraulic gate valve, normally seals and isolates chamber 34 from hopper 42. Conveyor 48 transports ore from a crusher station or ore pass, not shown, to hopper 42 which functions to measure and store a predetermined quantity of ore for rapid delivery into chamber 34.

A conduit 50 having a solenoid-actuated control valve 52 communicates chamber 34 with sump 54, pump 56 being employed to return displaced Water under pressure from sump 54 to annular column 14 via conduit 58 hav ing solenoid-actuated control valve 60.

Having generally described the components of an embodiment of the system of the present invention, we shall now describe the operation of the said system. A suflicient downward velocity is imparted to annular column 14 by pump 18 to overcome flow friction losses and the head unbalance between columns 10 and 14 due to loading of the hoisting column 10 with particulated ore. The columns are maintained in continuous communication with each other at their lowermost extremities thus ensuring a static balance therebetween. During the loading step of the cycle, ram 38 of valve 36 is actuated into its upper, closed position by piston-cylinder assembly thereby isolating columns 10 and 14 from chamber 34. Valve 52 is then opened allowing chamber 34 to depressurize to atmospheric pressure. A pressure solenoid switch then activates valve 44 which opens, allowing the measured quantity of ore in hopper 42 to fall by gravity into chamber 34. Valve 44 then closes. Valve 52 remains open permitting displacement of water from chamber 34 to sump 54 until the water level in the chamber has dropped to a predetermined operating level, the Water in sump 54 being transferred to annular column 14 by pump 56 and line 58. Some air cushion in the top of chamber 34 is maintained to modify pump pulsations. After valve 52 closes, valve 36 opens one inch allowing the pressure in chamber 34 to build up to equalize with the pressure in the hoisting column 10. This step is monitored by the pressure indicator and controller 62. When the pressures have equalized, valve 38 moves to its normally retracted at-rest position communicating columns and 14 with chamber 34 and permitting the ore in said chamber to be elevated by central column 10 to the upper delivery level and discharged into settling tank 22. Settled ore particles are removed and transferred to the mill for concentration while the water medium and fine solids are pumped to surge tank 28 for re-cycle; the coarser solids being removed automatically and added to mill feed, if density controller 33 indicates that the density of the re-cycled media is becoming too great.

Valve 60, in line 58, is regulated to remain open while pump 56 effects a positive flow of water into the annular column 14 from sump 54. Pump 56 operates independent of the remaining valves in the system and is activated by a level controller in sump 54. Valve 52 is interlocked with ram 38 and cannot open unless ram 38 is fully closed. Valve 44 is also monitored by controller 62 to ensure that said valve 44 will not open until the pressure in chamber 34 has dropped to atmospheric pressure.

With reference to FIGURES 2-4, embodiments of apex valve 36 will now be described. FIGURE 2 illustrates an embodiment wherein a peripheral ring 70 is secured about pipe 16 in proximity to the lowermost end of said pipe and is adapted to be engaged by the edge 71 of ram sleeve 72. Ring 70 preferably has an upper rigid portion 74 formed of steel and a lower portion 76 of a slighlty resilient material such as polytetrafluorethylene bonded to the steel which will form a water-tight connection with the edge 71 of sleeve 72. Sleeve 72 is adapted for vertical axial reciprocal movement within packing rings 78 which are secured to flange 80 at the tip of chamber apex 32. A piston rod 82 interconnects sleeve 72 within pistoncylinder assembly 40 illustrated in FIGURE 1. In the embodiment of FIGURE 2, central pipe 12 has an extension 84 secured thereto by a threaded coupling 86. Extension 84 has a helix 88 formed on its outer wall in the annulus defined between said extension and pipe 16 for imparting a rotational swirling motion to the descending liquid flowing in the said annulus.

FIGURE 3 illustrates another embodiment of apex valve wherein outer pipe 16 has a peripheral flange 90 formed perpendicular thereto at its lowermost extremity with depending guide fingers 92 formed vertically at its outer edge. Sleeve 94 is adapted to be reciprocated vertically substantially co-axial with pipe 16 by piston rod 82 for abutment of sleeve edge 95 with rubber seal 96 on flange 90 for providing a water-tight connection therebetween. Packing rings 97 provide a water-tight seal about the exterior of sleeve 94 adjacent end plate 97 secured to the apex flange 99 of chamber 34.

FIGURE 4 illustrates another embodiment of apex valve wherein a peripheral ring 98 having a rigid backing portion 100 formed of steel and facing material 101 such as polytetrafluorethylene is secured to pipe 16 on its exterior wall surface in proximity to its lowermost extremity. Ram sleeve 102 can be vertically axially reciprocated by rod 82 for engagement of the leading edge 104 of sleeve 102 with facing 101. The leading edge 104 of sleeve 102 preferably also is tipped with a sealing material such as polytetrafluorethylene to ensure a water-tight connection. Packing 106 is firmly positioned between sleeve 4 102 and sleeve housing 108 to prevent the entry of ore particles and leakage of water into chamber 34 when sleeve 102 is in its extended closed position. Water displaced from chamber 34 is returned to the system by conduit 60 which is secured to an inlet 110 of the housing 108 of chamber 113 defined below ram sleeve 102 by bottom wall 111. Ports 112 formed in the liner 114 of ram sleeve 102 permit the flow of water from conduit 60 into chamber 113 upwardly into the system of balanced liquid columns under static pressure. The upward flow of fluid through ports 112 assist the pick-up and elevation of ore particles into central hoisting column 10. Rod 82 passing through packing 116 secured to the exterior of wall 111 of chamber 113 operatively connects sleeve 102 to piston-cylinder assembly 40, not shown. A valved drain line 120 can be incorporated in the housing 108 to drain the system, if necessary.

It will be evident that the above embodiments of apex valve 36 permit uninterrupted circulation of liquid from annular column 14 to central column 10. The closing of the ram sleeves temporarily isolates the balanced columns 10 and 14 from chamber 34 thereby permitting loading of said chamber 34 with ore from hopper 42 at atmospheric pressure.

FIGURE 5 illustrates an embodiment of the system of the present invention wherein the water of annular column 14 by-passes loading chamber 122 in its downward travel. Column 14 defined between pipes 12 and 16 is blocked by means of an annular plug 126 and conduit 124 in communication with column 14 directs the water of column 14 to valve assembly 128 by means of inlet 130 wherein the water is directed upwardly through central port 132 formed within the ram sleeve 134. Sleeve 134 is axially aligned with extension 136 of inner pipe 12, extension 136 being centered within hamber 122 by a centering device 138. It will thus be evident that columns 14 and 10 will be continuously maintained in static balance when sleeve 134 is in its retracted position, as illustrated, or is extended into abutting engagement with the extension 136 of pipe 12 by actuation of piston-cylinder assembly 140.

FIGURE 6 illustrates the valve 128 in more detail wherein ram sleeve 134 has an axial port 132 formed therein defined by a bevelled inner wall 142, as illustrated. The upper portions of inner wall 142 and sleeve 134 are connected by an annular ring 144 having a resilient facing 146 formed of rubber, plastic or the like material on its upper surface. Facing 146 is adapted to abut the edge 148 of extension 136 when ram sleeve 134 is :axially reciprocated upwardly into engagement therewith by rod 135. Sleeve 134 is surrounded, in proximity to flanged connection 150, by packing 152. Rod is surrounded by packing 154 secured to the outside of plate 156 to prevent the escape of Water from the system. Inlet 130, in communication with conduit 124 described hereinabove with reference to FIGURE 5, permits introduction of water from annular column 14 t0 chamber 158 with vertical flow upwardly through port 132 into hoisting column 10 within pipe extension 136. Outlet 160 having a valve 162 positioned therein can be used to drain the system, if necessary.

FIGURE 7 illustrates an embodiment of apex valve similar to that illustrated in FIGURE 6 having a helix 164 secured longitudinally within port 132 for imparting a rotary swirling motion to water flowing upwardly into pipe extension 136. The swirling, turbulent motion of water rising upwardly to form part of hoisting column 10 assists pick-up of ore particles from the apex 163 of chamber 122 for elevation of the ore to the upper delivery level.

The valve embodiments of FIGURES 6 and 7 for use with the system of FIGURE 5 facilitates loading of the hoisting column 10 with ore by directing the water upwardly into the hoisting column against the underside of the ore particles. Also, piston-cylinder assembly 5. does not have to overcome the static pressure of the system, wihch can be substantial at great depths, in extending the ram sleeve to its upward closed position.

FIGURES 8, 9 and 10 illustrate an embodiment of the present invention particularly adapted for use in hoisting ore from an underground mine location. During the loading step of the hoisting cycle, apex valve 170 is closed by extending ram sleeve 172 axially upwardly by piston-cylinder assembly 173 whereby the upper end 174 of ram sleeve 172 abuts the lowermost end 178 of outer pipe 180; annular and central columns 182 and 184 being maintained in static balance as described hereinabove with reference to FIGURES 1-4. Ore fed by conveyor 186 to measuring hopper 188 drops by gravity into the cone bottomed chamber 190 upon the opening of gates 192 and 194. Gate 194 does not open until the pressure in chamber 190 has dropped to atmospheric pressure. The operation of valve 170 is controlled by the liquid pressure in chamber 190 which drops from normal hoisting pressure to normal circulating pressure upon completion of the hoisting of a batch of ore to the surface. Pressure monitor 196 automatically closes valve 170 upon a pressure drop and, when valve 170 is fully closed and properly seated, valve 198 opens automatically, permitting all the water in chamber 190 above the water control weir 200 to be displaced quickly under pressure from the compressed air 201 trapped in the domed roof 202 of chamber 190. This technique ensures that the ore contained in measuring hopper 188 will be transferred quickly to chamber 190 since the ore will fall more rapidly in air than through water.

Gate 192 functions as a pressure gate and gate 194 as a rock control gate, the latter protecting the pressure seats on gate 192 from damage that otherwise might result from the pressure seats being struck by falling rock. Gate 192 must be fully opened before gate 194 opens and, conversely, gate 194 must be fully closed and have arrested all rock movement before gate 192 closes. Gates 192 and 194 are actuated by hydraulic or electric-powered piston-cylinder assemblies 204 and 206 respectively. The side wall 208 of chamber 190 preferably is inclined at about 60 to the horizontal. This angle is in excess of the angle of repose of crushed ore and rock in water or in slurry form which is much greater than the angle of repose of like broken ore or rock in air, the angle of repose increasing as the density of the liquid medium increases.

During the charging of chamber 190, valve 194 remains open for a predetermined time suflicient to pass all the ore in pocket 188 into chamber 190. Valves 194 and 192 then close in the sequence described hereinabove. The closing of valve 192 automatically results in the closing of valve 198 in conduit 210 which results in the opening of valve 170 about one inch, thereby allowing the static pressure in chamber 190 to assume the static pressure of the hoisting column 184. When the pres-sure in chamber 190 equals the normal circulating pressure, as monitored by the pressure monitor controller 196, valve 170 assumes its normally retracted open position and hoisting of the ore in chamber 190 resumes.

Water displaced into sump 211 is returned to the system by pump 212 via conduit 214 which enters chamber 216 formed below ram sleeve 172, valve 170 being of the type illustrated in FIGURE 4. The water under pressure thus flows through port 218 upwardly into hoisting column 184. The resulting slurry received at the surface level is discharged into a de-watering bin 222 and conveyor-separator 223 for recovery of the water for recycle and concentration of the crushed ore for transfer to the mill. Hoisting column 184 flowing upwardly through central pipe 224 is discharged into the open-topped bin 222 by a plurality of conduits 226 fed by manifold pipe 228. The liquid level in bin 222 is controlled by overflow weir 230 in order to maintain a substantially constant head therein for discharge of slurry through spaced down pipe-s 232 at a constant rate to obviate overloading of conveyor-separator 223 due to surges in flow. The slurry discharged onto unit 223 separates into a liquid fraction which flows by gravity down the inclined surface of conveyor belt 234 to conduit 235 in communication with surge tank 236 for recycle under pressure by pump 238 to the system via annular column 182. Make-up water is added to the system by line 239.

Solids settle onto belt 234 and are conveyed up inclined belt 234 directly to the mill or to a loading hopper, not shown. Fine particles can be recovered from the water from conveyor-separator 223 by passing the water, under pressure, through a hydroclone, not shown, prior to delivery of the water to tank 236. Solids from the hydroclone, substantially de-watered, can be added to the ore on conveyor belt 234 above the unit 223. Excess water fed to unit 223 discharges through side opening 240 onto launder 242 and thence to surge tank 236. Unit 223 is substantially enclosed by cover 244 and end panel 246 at its lower end to prevent spillage of the slurry.

I have found a water medium having about 30% by weight fine solids, 200 mesh, provides a suitable slurry density for optimum lift of ore particles. The fine solids content of the slurry can be automatically controlled by the use of a hydroclone as described hereinabove. An ore-bearing slurry containing about 60% by weight solids, individual particle sizes being up to about 5 inches in diameter, can be readily elevated by an upward flow velocity of 7 to 8 feet per second in a 6 inch hoist pipe. A flow velocity of less than about 4 feet per second in fines-free water-media results in larger particles accumulating in the hoist column with eventual bridging and plugging while a flow velocity of more than 10 feet per second results in excessive friction losses.

The present invention provides a number of important advantages. The hoisting system can be readily adapted for installation in a mine opening such as a mine shaft, ventilation shaft, or bore hole to elevate crushed ore in a single or multiple stage lift from the underground workings to the surface. The system is simple and positive-acting in operation and can be automated for monitoring and control with a minimum of personnel, capital and operating costs being substantially below that of conventional ore hoisting systems such as skip hoists and the like.

It will be understood, of course, that modifications can be made in the preferred embodiments of the invention described and illustrated herein without departing from the scope of the invention defined by the appended claims.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. A hoist for discrete solids com-prising, in combination: two vertical Water columns arranged concentric with each other defining an upwardly moving central column and a downwardly moving annular column extending from substantially the same level at an upper delivery point to a level at a lower charge point so as to produce a static balance of the water in one column with the water in the other column; a pump in proximity to the upper delivery point adapted to discharge water to the downwardly moving annular column operable to impart a velocity to said annular column; a chamber formed in proximity to said water columns at the lower level having the chamber bottom extending below the central column; conduit means having a lower end in communication with said chamber and an upper end in communication with a feed hopper adapted to receive discrete solids at atmospheric pressure; first valve means formed in said conduit for isolating said chamber from the atmosphere; and second valve means formed in the bottom of said chamber adapted to isolate said water columns from said chamber while permitting circulation of water from the annular column to the central column and maintenance of the static balance.

2. In a hoist as claimed in claim 1, said chamber being concentric with said central Water column and having a cone-shaped bottom extending below said central water column.

3. A hoist for discrete solids comprising, in combination, two vertical water columns arranged concentric with each other defining an upwardly moving central column and a downwardly moving annular column extending from substantially the same level at an upper delivery point to the same level at a lower point so as to produce a static balance of the water in one column with the water in the other column; a pump in proximity to the upper delivery point adapted to discharge water to the downwardly moving annular column operable to impart a velocity to said annular column; a chamber formed about said water columns at their lower levels having the chamber bottom extending below the bottom of said water columns; conduit means having a lower end in communication with said chamber and an upper end in communication with a feed hopper adapted to receive discrete solids at atmospheric pressure; first valve mean formed in said conduit for sealing said chamber from the atmosphere; and second valve means formed in the bottom of said chamber adapted to seal said water columns from said chamber while permitting continuous circulation of water from the annular column to the central column and maintenance of the static balance therebetween.

4. In a hoist as claimed in claim 3, said chamber being concentric with said water columns and having a coneshaped bottom extending below said water columns.

5. In a hoist as claimed in claim 3, said pump adapted to receive water from the upwardly moving central column.

6. A hoist as claimed in claim 3 having means for transferring water from said chamber to said annular water column when said second valve is closed.

7. In a hoist as claimed in claim 4, means formed in the annular water column in proximity to the lower level for providing a rotational motion to said downwardly flowing annular water column.

'8. A hoist for hydraulically elevating discrete solids comprising, in combination: two pipes of substantially equal height of different diameters arranged concentric one within the other defining a central passage within the inner pipe and an annular passage between the inner and outer pipes extending from substantially the same level at an upper delivery point to the same level at a lower charge point, said pipes being in communication at the lower lever for providing a static balance between said pass-ages; a pump in proximity to the upper delivery point in communication with said central passage on its suction side and with said annular passage on its discharge side operable to impart a velocity head to a liquid flowing downwardly in said annular passage and upwardly in said central passage; a chamber formed about said pipes at the lower level having the bottom extending below the said lower lever, said inner pipe being open ended at its lower end for receiving a discrete solid from said chamber; conduit means having a lower end and an upper end, said lower end being in communication with said chamber and said upper end being in communication with solids storage means at atmospheric pressure; first valve means formed in said conduit for sealing the chamber from the atmosphere; and second valve means formed in the chamber for sealing said central and annular passages from said chamber while said first valve means is open permit-ting maintenance of the static balance between liquid in said annular passage and central passage.

9. In a hoist as claimed in claim 8, said chamber being formed concentric with said pipes at the lower level having a cone-shaped bottom with an apex extending below the said lower level.

.10. In a hoist as claimed in claim 8, said second valve means comprising an annular ring formed on the outer surface of the pipe defining the outer wall of said annular passage; closure means in axial alignment with said outer pipe adapted for reciprocal movement into and out of engagement with said annular ring for isolating said annular and central passages from said chamber, said closure means being adapted to permit continuous circulation of a liquid from said annular passage to the central passage.

11. In a hoist as claimed in claim 8, means comprising a helix formed in the annular passage for imparting a rotational motion to said downwardly flowing liquid.

12. In :a hoist as claimed in claim 8, said second valve means comprising a flange formed in the lower edge of said outer pipe defining an outwardly extending shoulder; downwardly extending depending fingers for-med on the outer periphery of said shoulder; a ram sleeve positioned in axially spaced relationship to said shoulder adapted to be displaced into abutting relationship with said shoulder for sealing and isolating said annular and central passages from said chamber and withdrawn from said shoulder for communicating said passages with said chamber.

13. In a hoist as claimed in claim 9, said valve means comprising a sleeve positioned in the apex of said conebottomed chamber in axially spaced relationship to said outer pipe, a peripheral shoulder formed on the upper end of said sleeve adapted to abut said outer pipe in liquid-sealing engagement, means for reciprocating said sleeve into and out of engagement with said outer pipe, and valved conduit means formed in said sleeve for supplying liquid to and discharging liquid from said sleeve.

14. A hoist for hydraulically elevating discrete solids comprising, in combination, two vertical liquid columns arranged concentric with each other defining an upwardly moving central column and a downwardly moving annular column in continuous communication at a lower level so as to produce a static balance of the liquid in one column with the liquid in the other column; a pump adapted to discharge liquid to the downwardly moving annular column operable to impart a flow velocity to said annular column; a chamber formed about said central column at its lower point having the bottom of the chamber extending below the bottom of said central column; conduit means having a lower end in communication with said chamber and an upper end in communication with a feed hopper adapted to receive discrete olids at atmospheric pressure; first valve means formed in said conduit for sealing said chamber from the atmosphere; and second valve means formed in the bottom of said chamber for sealing said liquid columns from said chamber while permitting continuous circulation of liquid from the annular column to the central column for main tenance of static balance between said columns.

15. In a hoist as claimed in claim 14, said annular column being isolated from said chamber by conduit means in communication with said annular column and said second valve means for continuously maintaining said annular column in static balance with said central column.

16. A hoist for hydnaulically elevating discrete solids comprising, in combination: two pipes of substantially equal height of different diameters arranged concentric one within the other defining a central passage within the inner pipe and an annular passage between the inner and outer pipes extending from substantially the same level at an upper delivery point to a lower charge point, said inner pipe extending below said outer pipe; first conduit means for communicating the annular passage with the central passage for providing a static balance between said passages; a pump in proximity to the upper delivery point in communication with said annular passage on its discharge side operable to impart a flow velocity to a liquid medium flowing downwardly in said annular passage and upwardly in said central passage; a chamber formed about said inner pipe at the lower point having the bottom of said chamber extending below the end of said inner pipe, said inner pipe being openended at its said lower end; second conduit means having 5 a lower end and an upper end, said conduit lower end being in communication with said chamber and said conduit upper end being in communication with solids storage mean at atmospheric pressure; first valve means formed in said second conduit for sealing the chamber from the atmosphere; and second valve means formed in the chamber in substantial axial alignment with said inner pipe for operative engagement with the lower end of said inner pipe for sealing said inner passage from said chamber while said first valve means is. open, permitting continuous maintenance of the static balance between the liquid medium in said annular passage and central passage.

17. In a hoist as claimed in claim 16, said second valve means having at least one port formed therein for continuously communicating said annular passage first conduit means with said central pas-sage.

References Cited by the Examiner UNITED STATES PATENTS 5/1957 Gardner 302-14 5/1965 Davies et al. 302-14 FOREIGN PATENTS 1,210,036 9/1959 France.

587,335 4/1947 Great Britain.

EVON C. BLUNK, Primary Examiner.

A. H. NIELSEN, Assistant Examiner. 

1. A HOIST FOR DISCRETE SOLIDS COMPRISING, IN COMBINATION: TWO VERTICAL WATER COLUMNS ARRANGED CONCENTRIC WITH EACH OTHER DEFINING AN UPWARDLY MOVING CENTRAL COLUMN AND A DOWNWARDLY MOVING ANNULAR COLUMN EXTENDING FROM SUBSTANTIALLY THE SAME LEVEL AT AN UPPER DELIVERY POINT TO A LEVEL AT A LOWER CHARGE POINT SO AS TO PRODUCE A STATIC BALANCE OF THE WATER IN ONE COLUMN WITH THE WATER IN THE OTHER COLUMN; A PUMP IN PROXIMITY TO THE UPPER DELIVERY POINT ADAPTED TO DISCHARGE WATER TO THE DOWNWARDLY MOVING ANNULAR COLUMN OPERABLE TO IMPART A VELOCITY TO SAID ANNULAR COLUMN; A CHAMBER FORMED IN PROXIMITY TO SAID WATER COLUMNS AT THE LOWER LEVEL HAVING THE CHAMBER BOTTOM EXTENDING BELOW THE CENTRAL COLUMN; CONDUIT MEANS HAVING A LOWER END IN COMMUNICATION WITH SAID CHAMBER AND AN UPPER END IN COMMUNICATION WITH A FEED HOPPER ADAPTED TO RECEIVE DISCRETE SOLIDS AT ATMOSPHERIC PRESSURE; FIRST VALVE MEANS FORMED IN SAID CONDUIT FOR ISOLATING SAID CHAMBER FROM THE ATMOSPHERE; AND SECOND VALVE MEANS FORMED IN THE BOTTOM OF SAID CHAMBER ADAPTED TO ISOLATE SAID WATER COLUMNS FROM SAID CHAMBER WHILE PERMITTING CIRCULATION OF WATER FROM THE ANNULAR COLUMN TO THE CENTRAL COLUMN AND MAINTENANCE OF THE STATIC BALANCE. 